Apparatus with rotating element for metal production



March 31, 1959 E. G. HELLIER 2,879934 APPARATUS WITH ROTATING ELEMENT FOR METAL PRODUCTION Filed Oct. 26, 1955 FIG.

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ATTORNEY United States Patent APPARATUS WITH ROTATING ELEMENT FOR METALPRODUCTION Edward G. Hellier, Hingham, Mass, asslgnor to NationalResearch Corporation, Cambridge, Mass., :1 corporation of MassachusettsApplication October 26, 1955, Serial No. 542,859

6 Claims. (Cl. 266-34) This invention relates to the production ofmetals and more particularly to the production of refractory metals suchas titanium, zirconium and the like. This application is in part acontinuation of my application Serial No. 442,525, filed July 12, 1954,now abandoned.

A principal object of the present invention is to pro vide improvedapparatus for growing relatively large crystals of a refractory metalsuch as titanium by the reduction of a compound of the refractory metaldispersed in a fused salt bath.

Another object of the invention is to provide apparatus of the abovetype which gives a relatively high yield of relatively large crystals oftitanium by the reduction of a titanium compound dissolved in a fusedsalt.

Other object of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the apparatus possessing theconstruction, combination of elements and arrangement of parts which areexemplified in the following detailed disclosure, and the scope of theapplication of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawing wherein:

Fig. 1 is a diagrammatic, schematic embodiment of one form of theinvention;

Fig. 2 is a diagrammatic, enlarged sectional view taken along the line2-2 of Fig. 1; and

Fig. 3 is a diagrammatic, sectional view taken along the line 33 of Fig.2.

The present invention is particularly directed to improved apparatus forthe production of refractory metals in the form of relatively largecrystals which can be readily water leached. For convenience ofillustration, the invention will be initially described in connectionwith apparatus specifically designed for the production of largecrystals of titanium by a process wherein a titanium halide, preferablya titanium lower chloride, is dissolved in a fused salt comprisingsodium chloride and this lower chloride of titanium is reduced totitanium metal by means of a reducing agent such as sodium. Thisspecific embodiment is given for illustrative purposes only withoutintent to limit the scope of the invention.

In a preferred form of apparatus embodying the invention, a chamber isprovided for holding a fused salt bath which contains a compound of themetal (e.g., titanium) to be produced. As mentioned above, this saltbath is preferably sodium chloride and a lower chloride of titanium ispreferably the dissolved titanium compound. The reactor also preferablyincludes a means for distributing the reducing agent (e.g., sodium) in auniform fashion across the surface of the fused salt bath so that thesodium can enter the bath uniformly across the whole upper surface, atleast during the initial stages of the reduction reaction. This sodiumdistribution means comprises a metallic element which is tions.

This disc-shaped element is mounted above the surface of the fused saltbath. The apparatus also includes means for rotating the disc-shapedelement about an axis which is substantially normal to the fused saltbath so that the disc rotates in a plane substantially parallel to thefused salt bath surface. Due to the cutaway portions, the circumferenceof the disc varies from a circle so as to provide portions thereofhaving dilferent radii. Means are also provided for feeding liquidsodium to the disc near its axis so that the sodium will traveloutwardly across the upper surface of the disc by centrifugal force.Since the sodium will leave the disc from various portions of thecircumference thereof which have different radii, the droplets of sodiumleaving the disc will have different horizontal velocities, thevelocities being a direct function of the distance from the axis to thepoints of departure.

The disc is also preferably provided with a means for assuring feed ofmost of the sodium to the points on the disc of greatest radii.Accordingly, the amount of sodium leaving any point on the circumferenceof the disc is a direct function of the square of the distance betweenthat point and the axis of the disc. This differential feed ispreferably achieved, in a preferred embodiment of the invention, byproviding spiral grooves on the upper surface of the disc, the spiralsbeing arranged to feed the greatest quantities of sodium tocircumferential points having the greatest radii. The arrangementdescribed above gives a particularly uniform distribution of sodium overa relatively large surface area of the molten salt. Since, in onepreferred embodiment, the level of the fused salt bath will rise duringthe reduction period, the apparatus also includes a means for measuringthe level of the fused salt bath. The apparatus also preferably includesa means for increasing the speed of rotation of the disc as the levelrises to give a flatter trajectory to the sodium droplets. Accordingly,the complete surface of the fused salt will be covered, even though thelevel thereof has risen substantially.

Referring now to the drawing, there is illustrated one embodiment of theinvention wherein 10 represents the reactor made of nickel or the like,having a top 12 which can be water cooled, if desired. In a preferredembodiment of the invention, the reactor is the type described in thecopending application of Vaughan, Serial No. 441,108, filed July 2,1954. The reactor includes a reaction space 14 containing a charge offused salt 16 which, in the preferred process mentioned briefly above,comprises a solution of lower titanium chlorides in sodium chloride. Thereactor may also contain a grid 17 for supporting the titanium crystalsformed during the reduction operation. The means generally indicated at18 for distributing the sodium over the surface of the fused salt 16preferably includes the disc-shaped metallic element 20 carried by arotatable shaft 22 and a feed tube 24 for feeding sodium 25 to discelement 20. The shaft 22 is driven by a variable speed motor 21controlled by a suitable level-measuring device. This level-measuringdevice is preferably a radioactive source 23a arranged to be scanned bya radiation-sensitive element 23. One such method of level measurementis shown in US. Patent 2,647,826 to Jordan. As the level of the meltrises, the level-measuring device 23 increases the speed of the motor 21so that the area covered by the fed sodium remains substantiallyconstant even through the distance between the disc 20 and the surfaceof the salt bath decreases. As seen best in Figs. 2 and 3, disc element20 has cutaway portions 26 so that the circumference of the disc-shapedelement 20 is not a circle but has circumferential portions of differentradii capable of imparting different horizontal velocities to droplets25 of sodium flung from the disc at the points of different radii. Thedisc-shaped element 20 also preferably includes spiral grooves 28 whichare so designed as to cause larger amounts of sodium to be thrown frompoints of the greatest radii with respect to the shaft axis. In otherwords, most of the sodium is fed to those points on the circumference ofthe disc 20 which are spaced the farthest distances from the axis 22. Ascan be seen best in Fig. 3, the spiral grooves 28 are so designed thatthe size of the groove increases as a function of its length. Thus thegrooves extending to the outer portions of element 20 are the deepest soas to carry the greatest amount of sodium. The same effect can beachieved by varying the width of the grooves. Alternatively, the spiralscan be of uniform size with more spirals being provided for feedingsodium to each unit of circumference as the radius increases.Accordingly, the amounts of sodium thrown from the various points on thedisc increase with the square of the radii of these points so that thesodium will fall uniformly on the surface of the melt 16.

The above arrangement provides a solid cone of sodium spray which coversthe surface of the molten salt bath. As the level of the salt bathrises, the cone is flattened by increasing the shaft speed so thatsodium is still fed to the outer circumference of the bath.

In a preferred embodiment of the invention, the disc 20 and shaft 22 arepreferably formed of titanium, this being particularly true whentitanium is the refractory metal to be produced and when any titaniumtetrachloride is present. This latter condition will be found in thosecases where titanium tetrachloride vapor is reduced to titaniumdichloride or titanium trichloride by sodium within the reactor 10, thisbeing one preferred method of making the mixture of titanium dichlorideand sodium chloride. In this method of operation, a feeding tube (notshown) may be provided for feeding the titanium tetrachloride into thereactor 10. In this embodiment of the invention, it is also preferred toprovide a stirrer (not shown) for agitating the molten salt bath 16during the formation of the sodium chloride-titanium dichloride mixture.While titanium is the preferred metal for constructing the disc 20 andthe other elements of the sodium feed system, other refractory metalssuch as zirconium, tantalum and the like may be employed. Additionally,while a fiat disc is the simplest type of construction, it should beapparent that the element may take the shape of a pyramid or conewithout detracting from the essential features of the invention.Equally, numerous modifications of the specific type of spiralillustrated can be provided.

Since certain changes may be made in the above apparatus withoutdeparting from the scope of the invention herein involved, it isintended that all matter contained in the above description, or shown inthe accompanying drawing, shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:

1. Apparatus for producing crystalline refractory metal by reduction ofa refractory metal compound dissolved in a fused salt bath, theapparatus comprising a reaction chamber for holding a fused salt bath, ametallic element mounted above the surface of the fused salt bath, meansfor rotating the element about an axis sub stantially normal to thefused salt bath so that the element rotates in a plane substantiallyparallel to the fused salt bath surface, and means for feeding a liquidmetal reducing agent to the element near the axis of rotation thereof,the circumference of the element varying from a circle to provideportions of different radii capable of imparting different horizontalvelocities to droplets of reducing agent flung from the element at thepoint of different radii.

2. Apparatus for producing titanium by reduction of a titanium compounddissolved in a fused salt bath, the apparatus comprising a reactionchamber for holding a fused salt bath, a titanium disc mounted above thesurface of the fused salt bath, means for rotating the disc about anaxis substantially normal to the fused salt bath so that the discrotates in a plane substantially parallel to the fused salt bathsurface, and means for feeding a liquid metal reducing agent to thedisc, the circumference of the disc varying from a circle to provideportions of different radii capable of imparting different horizontalvelocities to droplets of reducing agent flung from the disc at thepoints of different radii.

3. Apparatus for producing crystalline refractory metal by reduction ofa refractory metal compound dissolved in a fused salt bath, theapparatus comprising a reaction chamber for holding a fused salt bath, ametallic disc mounted above the surface of the fused salt bath, meansfor rotating the disc about an axis substantially normal to the fusedsalt bath so that the disc rotates in a plane substantially parallel tothe fused salt bath surface, and means for feeding a liquid metalreducing agent to the disc, the circumference of the disc varying from acircle to provide portions of different radii capable of impartingdifferent horizontal velocities to droplets of reducing agent flung fromthe disc at the points of different radii, the means for feeding theliquid metal reducing agent to the disc and the surface of the discbeing arranged to provide feed of the greatest amounts of liquidreducing agent to points of greatest radii on the disc.

4. Apparatus for producing crystalline refractory metal by reduction ofa refractory metal compound dissolved in a fused salt bath, theapparatus comprising a reaction chamber for holding a fused salt bath, ametallic element mounted above the surface of the fused salt bath, meansfor rotating the element about an axis substantially normal to the fusedsalt bath so that the element rotaes in a plane substantially parallelto the fused salt bath surface, and means for feeding a liquid metalreducing agent to the element, the circumference of the element varyingfrom a circle to provide portions of different radii capable ofimparting different horizontal velocities to droplets of reducing agentflung from the element at the points of different radii, the surface ofthe element having grooves for guiding the liquid metal outwardly in anon-uniform fashion so that the amount of reducing agent leaving a pointon the circumference having a given radius is a direct function of thesquare of the radius at that point.

5. Apparatus for producing crystalline refractory metal by reduction ofa refractory metal compound dispersed in a fused salt bath, theapparatus comprising a reaction chamber for holding a fused salt bath, ametallic element mounted above the surface of the fused salt bath, meansfor rotating the element about an axis substantially normal to the fusedsalt bath so that the element rotates in a plane substantially parallelto the fused salt bath surface, and means for feeding a liquid metalreducing agent to the element, the circumference of the element varyingfrom a circle to provide portions of different radii capable ofimparting different horizontal velocities to droplets of reducing agentflung from the element at the points of different radii, the elementhaving spiral grooves on the upper surface thereof for feeding thegreatest quantities of reducing metal per unit of circumference toportions of the element of greatest radius, the amount of reducing agentfed from a given point being a direct function of the square of thedistance between that point and the axis of the element.

6. Apparatus for producing titanium by reduction of a titanium compounddissolved in a fused salt bath, the apparatus comprising a reactionchamber for holding a fused salt bath, a titanium disc mounted above thesurface of the fused salt bath, means for rotating the disc about anaxis substantially normal to the fused salt bath so that the discrotates in a plane substantially parallel References Cited in the fileof this patent UNITED STATES PATENTS Butcher et al. June 4, 1867 VonPazsiczky Sept. 1, 1942 Truthe Dec. 8, 1942 Landgraf Aug. 22, 1944Hancox et a1 Mar. 13, 1951 Jordan Aug. 4, 1953

1. APPARATUS FOR PRODUCING CRYSTALLINE REFACTORY METAL BY REDUCTION OF AREFRACTORY METAL COMPOUND DISSOLVED IN A FUSED SALT BATH, THE APPARATUSCOMPRISING A REACTION CHAMBER FOR HOLDING A FUSED SALT BATH, A METALLICELEMENT MOUNTED ABOVE THE SURFACE OF THE FUSED SALT BATH, MEANS FORROTATING THE ELEMENT ABOUT AN AXIS SUBSTANTIALLY NORMAL TO THE FUSEDSALT BATH SO THAT THE ELEMENT ROTATES IN A PLANE SUBSTANTIALLY PARALLELTO THE FUSED SALT BATH SURFACE, AND MEANS FOR FEEDING A LIQUID METALREDUCING AGENT TO THE ELEMENT NEAR THE AXIS OF ROTATION THEREOF, THECIRCUMFERENCE OF THE ELEMENT VARYING FROM A CIRCLE TO PROVIDE PORTIONSOF DIFFERENT RADII CAPABLE OF IMPARTING DIFFERENT HORIZONTAL VELOCITIESTO DROPLETS OF REDUCING AGENT FLUNG FROM THE ELEMENT AT THE POINT OFDIFFERENT RADII.